1. Field of the Invention
The present invention relates to a power off method for a wireless device and, more particularly, to a power off method for a wireless device, whereby signals emitted from a wireless device can be successfully received by a wireless receiver after completing the identification process between the wireless device and the wireless receiver.
2. Description of the Related Art
Because of rapid advancement in the field of wireless transmission technology, the immunity to external interference has greatly enhanced and the transmissible distance has also significantly extended. Base on these advantages, the wireless transmission technology has been applied and integrated to computer peripherals, such as wireless mice and wireless keyboards in computer systems.
A wireless mouse is presented here as an example to illustrate the proper operation between computer and a wireless computer peripheral device. The wireless mouse generally requires an independent power source such as a standard alkaline battery or a rechargeable battery to drive all the necessary function. The wireless mouse can be automatically turned on when battery is loaded. Alternatively, the wireless mouse can also be manually turned on/off by operating an additional power switch.
Refer to FIG. 1; in order for computer 63 to be able to receive the signals emitted from the wireless mouse 61, a wireless receiver 62 is employed and connected to the computer 62. The wireless mouse 61 stores an ID code to facilitate the identification by the wireless receiver 62. The wireless receiver 62 can hence properly identify the signals emitted from wireless mouse 61. In order to shield the wireless mouse 61 from the external interference caused by other wireless devices (e.g., other wireless mouse or wireless keyboard) in the vicinity, the wireless mouse 61 generally stores several sets of ID codes. The internal code returns to its default value every time the wireless mouse 61 incurs a power reset. Therefore, it is necessary to first execute an ID code synchronization process with the accompanied wireless receiver 62 by pressing a connect button (not shown). Subsequently, various operations of the wireless mouse 61 are accurately accepted by the wireless receiver 62 and then sent to the computer 63.
However, after the wireless mouse 61 has idled for a certain period of time, in order to save the battery power, the wireless mouse 61 enters a power-saving mode (sleep mode). Even the wireless mouse 61 has entered into sleep mode to save power, it is still likely to be inadvertently waked up by a heavy shake, or a touch on the mouse button happens to be made by the vicinal objects during travel.
Hence, the internal battery of the wireless mouse 61 is either removed or disconnected for traveling purpose. The internal ID code of the wireless mouse will go back to the reset value at the time the power source of the wireless mouse is re-connected. And a process of ID code synchronization between the mouse and the receiver has to be conducted again. It is really an undesirable waste of time for repeatedly doing the synchronization process every time the power source is reconnected.
In order to solve the problem of returning ID code to reset value due to the power interruption, a nonvolatile memory is employed by some wireless products to perpetually keep the ID code. Although this is a feasible solution to the above-mentioned dilemma, the I/O pin count of the mouse controller has to be increased for connecting to the nonvolatile memory. The increasing in I/O pin count also increases chip size and cost.
Accordingly, the present invention aims to propose a power off method for a wireless peripheral device to solve the problems experienced in the prior art.